REFERENCE TOOLS

InfoSpace - World e-mail & telephone directories, reverse lookup, white & yellow pages
United States Postal Service ZIP Code Lookup - ZIP+4 codes, all ZIP codes for a city/town, all cities/towns in a ZIP code
WhitePages.com - Phone number & address lookups & directories for people, businesses, e-mail, ZIP codes, area codes, & international calling codes

Encyclopedias

General Reference Sites